[Mac] Allow more CVMS file object reads in the 10.14 sandbox.

Beta 3 18A326g added new locations for CVMS files.

Bug: 850021
Test: Form controls render correctly in web content.
Change-Id: I00f93a847d1dbb086edea318526aab74bddb54bc
Reviewed-on: https://chromium-review.googlesource.com/1130163
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573837}

services/service_manager/sandbox/mac/renderer_v2.sb

@@ -21,8 +21,10 @@
 ; Reads of signed Mach-O blobs created by the CVMS server.
 ; https://crbug.com/850021
 (if (>= os-version 1014)
-  (allow file-read-data
-    (prefix "/private/tmp/cvmsCodeSignObj")))
+  (allow file-read*
+    (extension "com.apple.cvms.kernel")
+    (prefix "/private/tmp/cvmsCodeSignObj")
+    (subpath "/private/var/db/CVMS")))
 
 (allow file-write-data
   (require-all